Automatic variable pitch propeller



July 12, 1938. D. e. LILLEY 3 9 AUTOMATIC VARIABLE PITCH PROPELLER Filed July 29, 1935 3 sheets-Sheet 2 INVENTOR. flA/V/EL G. L/LLEY y 2, 1938'. D. G. ULLEY 2,123,193

AUTOMATIC YARIABLE PITCH PROPELLER Filed July 29; 1935 3 Sheets-Sheet 5 INVENTOR. DAN/EL G. L/Lfy Patented July '12, 1938 PATENT OFFICE 2,123,195 AUTOMATIC VARIABLE PITCH PROPELLER Daniel G. Lilley, DeriveryColo.

Application July 29,

2'7 Claims.

This invention relates to improvements in variable pitch propellers for use with aeroplanes.

It is well understood that for the best results and the most efficient operation of aeroplanes it is necessary to be able to change the pitch of the propeller in accordance with its speed, so as to retain the optimum angle of attack at all times.

When an'aeroplane is standing still theangle of attack is the actual pitch of the aeroplane, but as the plane begins to move, the resultant angle of attack becomes smaller and if the speed could bc continuously increased, it would soon become equal to the pitch times the number of revolutions per unit of time, and the resultant angle directly by the pilot, or automatically by the speed of the propeller or by its tractive eifort.

It is the object of this invention to produce a variable pitch propeller that will automatically adjust the propeller blades to low pitch when taking-off from the ground, and when climbing,

and which will automatically increase or advance the pitch when the ship has reached its altitude and settled down to a cruising speed.

It is another object of. this invention to produce a pitch varying mechanism that shall operate automatically and which can also be changed by the pilot, whenever he desires to do so, by merely accelerating or de-celerating the drive shaft.

This invention, briefly described, comprises a mechanism, includingan inertia member that is supported by the drive shaft and mounted so as to have a limited rotation relative to the drive shaft and about its axis, and means interposed between the inertia member and the propeller blades for .turning the latter about their axes whenever the inertia member rotates relative to the drive shaft, the direction in which the pitchis adjusted depending on the direction in which. the inertia member rotates relative to the drive shaft.

Having thus, briefly, described the invention,

1935, Serial No. 33,736

Figure 1 is a front elevation of, a propeller hub embodying my invention, and showing portions thereof broken away'to better disclose the construction;

Figure 2 is a section taken on line 2-2, Figure 1;

Figure 3 is a section similar to that shown in Figure 2, and shows'a slightly modified form of the invention;

Figure 4 is a section similar to that'shown in Figure 2, but showing a slightly modified construction; I Figure 5 is a fragmentary section showing another modification;

Figure 6 is a section taken on line 66, Figure 2;

- Figure 7 is a section taken on line 1-1, Figure 1;

Figure 8 is a view showing a still further modi-' fication;' and Figure 9 shows a still further modification.

In the drawings, reference numeral I0 desig ates the crank shaft of an engine, and H the wall of the crank case which is provided with a bearing l2. In the embodiment illustrated in Figure 2, the crank case is provided with a compartment l3 whose outer wall has been designated by numeral I4, and whose end walls have been designated by numerals I5 and 'l6. Wall M has a bearing I! for the crank shaft. That portion of the crank shaft that lies between walls I l and I4 is branched and formed by two 'U-shaped portions whose bases have been designated by reference numeral l8.

The crank shaft has a tubular portion I3 that extendsforwardly from the bearing I1, and is provided on its outer surface with splines 20. A hub member 2| is splined to the shaft, and has its ends provided with circular splined portions 22 and 23, for the reception of the hub' members 24 and 25. Hub member 2| is provided at diametrically opposite points with circular projections 26, one of. which is shown in Figure 1, and which form supports for the inner race ring 21 of a roller bearing having rollers 28 and an outer race 29. i The parts 24 and have semi-circular extensions 3|] which, when assembled, form tubular extensions whose inner surfaces comprise cylindrical surfaces "3|, 32, 33, 34 and 35, of different diameters.

Located with its outer surfaceadjacent the inner cylindrical surface 3| is a thrust bearing 36, and located with its. outer race in contact with the cylindrical surface 35 is a ball bearing 31. Located in each tubular extension is a cylindrical member 38 having a radial flange 39, that rests against one race of. the thrust bearing a 36. The outer end of the cylindrical portion of member 38 is supported by the inner race of bearing 31. A threaded ring 40 holds the bearing 31 in place.

Member 38 is provided with several openings through which the rods 4| extend. The inner ends of rods 4| rest against the race 29, and the outer ends are engaged by a ring 42 which is threaded to the outer end of part 38 and by means of this the race 29 can be moved inwardly to adjust for'wear. The bottom of member 38 has a central cylindrical projection 43 and its inner surface is threaded for engagement with the root portion 44 of a propeller blade which is held against rotation by some suitable means, not shown.

In the embodiment shown in Figures 1 and 2, arms 45 extend radially from the flanges 39 and project through slots 46 in the hub member 24, (see Figure '7) When the arms 45 are moved in slots 46, the propeller blades are rotated about their axes so as to change their pitch angle.

The front end of the drive shaft is provided with diametrically positioned slots 41 for the reception of the worm gears 48 that are carried on shafts 49. These shafts are journalled in suitable bearings lying on opposite sides of'the drive shaft and terminate in eccentrics 50. A connecting rod connects each eccentric with the outer end of a crank arm 45, as shown in Figures 1. and 7. The eccentrics are oppositely arranged so as to impart equal and corresponding rotation to the two propeller blades.

An auxiliary shaft 52 extends through the axial opening in the end 2| of the drive shaft, and through the space between the sides of the U- shaped branches l8 and I8 of the drive shaft. Anti-friction bearings 53 and 54 are provided for the auxiliary shaft. Shaft 52 is provided at its front end with a smooth section that carries a worm 55 and this terminates in a flange 56 against the rear surface of which the ball bearing 57 rests.

The shaft is provided with a double pitch square thread that extends to the rear end and which has been designated by reference numeral 58. A nut 59 is in threaded engagement with the shaft and has its periphery in operative engagement with the splines 60 on the inner surface of the opening in the drive shaft.

A helical compression spring 6| encircles the shaft-52 between the nut and the bottom of the opening. Secured to that portion of the shaft that passes through the space between the U-shaped offsets l8 of the drive shaft is a hub 62 that has a splined connection with the shaft at this point and which is provided with a flange 63. Mounted for rotation on the hub is a circular in ertia member or fly wheel having a rim 64 and an inwardly extending web 65 that terminates in a tubular hub 66. l

A spring 61 surrounds the hub 66 and is held under compression by the flanged nut 68 and forces the web 65 against the flange 63 so as to form a friction clutch that permits the inertia member to rotate without rotating shaft 52, if the latter offers too much resistance. The rim 64 has a plurality of pairs of openings 69 for the reception of removable plugs 10, which may be made of lead or other heavy metal.

The openings are arranged in diametrically opposed pairs and the two openingsof each pair are of the same diameter, and the diameters of the openings in the several pair are different for each pair so as to assure that the proper plugs are located in each pair of openings. It may be desirable to have each opening of a different diameter so that there will be no possibility of interchanging the plugs as' it is essential that this device shall be very carefully balanced.

Attention is called at this point to the fact that the worm wheels 48 have teeth on a portion only of their peripheries, and that the ends of the worm55 will therefore strike the sides of these.

wheels at the end of a certain number of revolutions of shaft 52 so as to limit its rotation in both directions. As above explained, when shafts 49 rotate, the eccentrics 50, acting through the connecting rods 5|, change the pitch of the blades, and as the maximum change is effected by a rotation of 180, this is the extent of the rotation required of shafts 49.

Let us now assume that the parts are stationary, and in the position illustrated in Figures 1 and 2, which position corresponds to the most advanced pitch.

Let us now assume that the motor is started so as to rotate the shaft in a counter-clockwise direction, looking toward the propeller from a position to the front thereof.

The inertia member naturally tends to lag and as the speed of the drive shaft is accelerated the auxiliary shaft will have a clockwise rotation with respect to the drive shaft when viewed from the same point.

Since the nut 59 turns with the drive shaft it will move toward the right (Figure 2) as the drive shaft is accelerated, to reduce the pitch to a minimum at which point the forward end of the worm 55 will strike against the surface of the lower wheel 48. It will be observed that as the nut 59 moves toward the right it will compress the spring 6| which therefore offers a yielding and increasing resistance to the change of the pitch from a maximum to a minimum. 1

After the aeroplane has ceased climbing, the motor is slowed down but the inertia member continues to rotate at the same speed, or at least does not decelerate as fast as the drive shaft, with the result that the auxiliary shaft is now turning in a counter-clockwise direction, relative to the drive shaft, and the nut 59 moves toward the left (Figure 2) and if the deceleration of the drive shaft continues for some time, the parts will return to the position shown in Figure 2 or to the maximum pitch position.

The pilot can control the pitch by merely accelerating and decelerating the drive shaft. If the pitch is too high, he can accelerate sharply until the pitch is reduced to the desired value, and if he then decelerates slowly until the desired speed is attained, the resistance of the parts will be sufficient to produce the same deceleration of the inertia member. In the same manner he can increase the pitch by decelerating the drive shaft quickly, which causes the inertia member and shaft 52 to overrun the drive shaft and increase the pitch and he can then increase the speed so gradually that the friction of the parts and the resistance offered by the spring will produce suflicient force to accelerate the inertia member at the same rate.

In order that the pilot may know at all times at what pitch the propellers are operating, an indicator has been provided, and this will now be described.

Bars II project over the hub portion 2| and this is provided with a plurality of rods I2 that extend through the wall of hub member 25, and are attached to a ring I3. Springs I4 surround the rods I2, and keep the bars "II in contact with pins I5 that are carried by the root portions of the propellers.

Some means such as a lever I6, which is pivoted at II, has itsinner end urged against ring I3 by the action of the spring 18. Ailexible member I9 connects the free end of lever I6 with the pivoted pointer 80 that is located on the instrument board and .biased in one direction by a; spring 8|. The apparatus just described can, of course, be replaced by any other suitable apparatus.

In Figure 3 a modification of .the construction above described has been shown. In this embodiment the inertia member has been placed to the front of the propeller. A steel casting or forging 82 is provided with a central threaded ,hub 88 that is threadedly connected with the axial opening in the shaft portion I9. Member 82 has a shoulder 84 that engages the end of the hub, and the inner end of him 83 forms an abutment for the ball race 85. Shaft 52a has a flange 86 that engages the other ball race. rear end of shaft 52a has an axial cylindrical extension 81 and.the part between the flange 86 and the end is provided with left hand threads and carries the nut 59 which cooperates with the splines 88 that permit the nut to move longitudinally, but hold it from turning.

The front end of shaft 52a is of reduced diameter and is mounted in a ball bearing 89. A hub 90 is splined to the end of the shaft, and held in place thereon by a nut 9I. Arms 92 extend radially from the hub and carry weights 93 that are held in radially adjusted position by lock nuts 94. The assembly comprising the weights 93 forms an inertia member which corresponds in function to the one illustrated in Figures 2 and 6. The operation of the .device illustrated in Figure 3 is exactly the same as that illustrated in Figure 2 and already described. The friction clutch, shown in Figure 2, has been omitted in the construction illustrated'in Figure 3, but may be added ifdesired.

6o; ing 51 are the same as in Figure 2. Instead of the worm 55, shaft 522) has a threaded section 96 In Figure 4 another modification has been shown; in this construction the wheels 48 and the shafts 49 and also the eccentrics 58 and connecting rods 5| have been omitted. A shaft 52b, which corresponds to shaft 52 in Figures 1 and 2 and to shaft 52a in Figure 3, is located in axial which is connected with a threaded and splined hub 91, from which two arms 98 extend radially;

these arms pass through slots 99 in the end of the propeller shaft. Secured to the end of each arm is abar I00, one only being visible in the drawings. Each bar hasaprojection I-0I to which a connecting rod I02 is pivoted.

The flange 39 of the blade socket 38 has a radial arm I03 towhich the other end of the-connecting rod is pivoted.- When the arms 98 and bars I0ll-move toward the right, in Figure 4, the pitch of the propellers will be increased. A circular ball race I04 is attached to the front end The of the drive shaft and cooperates with another ball race I05, carried by shaft 52b.

A hub I06, which corresponds to hub 62 shown in Figure 2, is splined to the auxiliary shaft and has a radial flange I0I,.which forms one part of a friction clutch. Mounted for rotation on the hub I06 is an inertiajmember comprising a hub I08 having a'radial flange I09 and one or more pair of diametrical radial arms llflwhich correspond to arms 92, shown in Figure 3, and which carry weights I II that can be adjusted as to their radial position and held in adjusted position by means like that shown in Figure 3.

It is apparent that if the auxiliary shaft is rotated in a counter-clockwise- 'direction withr respect to the drive shaft, when viewed from the left end of Figure 4, hub 91 and arms 98 will move toward the right and increase the pitch of the propeller blades, and at the same time the nut 59-will move toward the left thereby permitting spring 6I to expand.

It will be observed that flange 56 is provided with a lug H2 and the rear end of hub 91 with a lug II3, and therefore, when the'hub 9'! approaches near enough to the flange 56, the two when the hub moves forwardly these two lugs will I overlap and form a stop which limits rotation of the auxiliary shaft. When the auxiliary shaft is stopped, the inertia member may continue to rotate for a short distance by virtue of the friction clutch.

'It is believed that the operation of the device shown in Figure 4 and which has just been described will be apparent from the description of the operation of the form illustrated in Figure 2.

In Figure 5, another form has been shown and in this a shaft III has been shown as threaded in the opening in the end of drive shaft I9.

Shaft III has a flange II8 that engages the end of the hub. Although the shaft III has been shown as formed from a separate piece, it may, in fact, bean integral extension of the drive shaft. The fr'ont end of shaft II! is provided with threads II9 with which a nut 58 cooperates. A tubular auxiliary shaft 520 surrounds the outer end of shaft' III and the wall of the cylindrical opening is provided with splines a which 00- operate with corresponding spline grooves on the nut 59. Near the rear end of shaft 520 is an inwardly extending flange I20, and located between this and flange H8 is an anti-friction bearing I2I.

An anti-friction bearing I22 is positioned be: tween the auxiliary shaft 520, and the front end of shaft I II. A ring I23 is located directly to the rear of the bearing I22, and serves as one abutment for the spring 6|, "whose other end abuts the nut 59. The outer surface of the tubular shaft is provided with a flange I24, that faces forwardly and is mounted on the auxiliary shaft; in front of the flange I24 is a hub 108a that corresponds to hub I08 in Figure 4, and from this hub a flange or web I09a extends,

A flange I25 is slidably b-ut'non-rotatably mounted on the front end of the auxiliary shaft, and is acted upon-by a compression spring I 26 that is located between the movable flange and the nut I21. The parts just described form a friction clutch, and a similar clutch has been illustrated in Figure 4, and similar reference numbers applied to the spring and the nut. A

theleftor-from in front of the propeller; this will move the arms 98 and 98a toward the right and increase the pitch angle, and at the same time, nuts 59 will move so as to allow the springs 6| to expand. Adjustments of the pitch can be made at any time by properly accelerating and decelerating the drive shaft as above explained.

In Figure 8 another embodiment has been shown for the purpose of illustrating the invention in an extremely simple form. In this embodiment, the end I9 of the drive shaft is provided with an axial opening I28 with which is.

threade'dly connected an auxiliary shaft 52d. A spring Gld is located in the opening between the rear end of the auxiliary shaft and the bottom of the opening. A fly wheel or inertia member I29 is connected with the front end of the auxiliary shaft and the latter is surrounded by a perforated plate I30, which is positioned between two stationary flanges I3I. Bars IIlIld connect the ends of member I30 with the ends of crank arms 45d, which are connected with the propeller blades as shown in Figure 7.

When shaft 52d is rotated relative to the drive shaft, it will move forwardly or rearwardly, depending on the direction of the relative rotation, and this movement will be imparted to member I30 by the flanges I3I and the forward or rearward movement of member I30 will effect a change of pitch of the propeller blades, The parts are' so related that the spring Bld will tend to assist the movement in a direction to increase the pitch.

-In Figure 9 another modification has been shown that is a variation of that shown in Figure 8, but in which the end I9 of the propeller or drive shaft has an axial opening for the reception of'the end I32 of a plug whose outer end is provided with a threaded section I33 of suitable pitch.

, A flange I34 projects outwardly between sectionsv I32 and I33. Suitable means may be provided to secure the plug in place. It is also evident that the threads can be provided on a cylindrical portion of the drive shaft itself.

Carried by the threaded section I33 is an inertia member having a threaded hub I34, that is operatively connected with the threads. The threaded end of the plug is preferably provided with some longitudinally extending spline grooves which have been indicated by numeral I35. A nut I36 is threaded to the front end of the plug and that portion between the nut and the front of the connecting rods are pivoted to the ends of the radial arms I45 which are connected with the root portions of the blades and pass through the slots I46 in the hubs I41. A cap I48 is secured to the collar I43 by bolts I49, and has an opening for the reception of the threaded end of the plug. The wall of the opening has projections that engage the spline grooves I35 and holds the collar from rotation about the axis of the drive shaft and relieves the connecting rods of strains.

In the position shown in Figure 9, the blades are in maximum pitch, which position is automatically assumed in all of the modifications shown, whenever the drive shaft slows down or stops rotating.

For effective operation of the device for any desired propeller performance, the pitch of the threads of the auxiliary shaft and nut, the strength of the compression spring, the weight and adjustment of the inertia member, and the degree of drive shaft acceleration at which it is intended that the device should operate, are all factors that would have a very close relationship in the performance of any given propeller.

The inertia weights are shown as being adjustable to change the value of the inertia member and its force development per unit acceleration to take care of any variation in the amount of effort required to rotate the blades of different propellers or to synchronize propellers where more than one is used on a ship.

One of the principal purposes of the threaded auxiliary shaft, nut and compression spring, is to keep the inertia member rotating with the drive shaft at cruising speeds, and to prevent the parts from creeping into low or intermediate pitch positions, due to pulsations of the motor, but these parts should not exert enough force to preventmovement of the inertia member relative to the drive shaft under any desired degree of engine acceleration at which it is desired to .change the blades toward minimum pitch.

degree of engine and drive shaft acceleration for taking off and climb, the blades automatically returning to maximum pitch as soon as the engine speed is slightly reduced, after which the pilot could steadily increase the engine speed without any fear of the blades coming back toward intermediate or minimum pitch, the parts first having been proportioned to reduce the blade pitch only by a very high degree of drive shaft and engine acceleration.

Figure 8 is illustrative of oneway in which the adjustment can be effected by a longitudinal movement of the auxiliary shaft, although it has been illustrated as having both a longitudinal and rotary movement.

From the above it will be seen that the invention can be embodied in many specifically different forms, all of which have this in common, that they are each provided with an inertia member or fly wheel, that is mounted for rotation about the center of the drive shaft and connected with the propeller blades by some means that translates the relative rotarymovement of the inertia member and the drive shaft into a rotary movement of the blades about their axes.

When the drive shaft is accelerating, a relative rotation takes place between it and the inertia member which moves thepropeller blades toward low pitch. When the drive shaft and the inertia andthe speed of the drive shaft is slowed down member are rotating at the same rate of speed the inertia member over-runs the drive shaft, thereby again causing relative movement between the drive shaft and the inertia member which rotates the blades back into maximum pitch position. L

It will be observed that the tension spring cooperates with the inertia member, or at least does not hinder the inertia member in its effort to rotate the blades from minimum to maximum pitch whenever the driveshaft speed is somewhat reduced.

Attentionis directed to Figure 2, from which it will be seen that the inertia member is enclosed in a housing l5, which rotates with the drive shaft. It will be seen from this that the operation is entirely independent of air resistance. In Figures 3, 4, 5, 8 and 9, the inertia members are shown exposed, but in the actual design a shield would be provided about the mechanism that is shown exposed. Air resistance is a detriment as it resists the rotation of the inertia member, and interferes to some extent with the relative rotation of inertiamember and shaft, when the latter decelerates.

It is apparent'that by reversing the motion transmitting mechanism between the inertia member and the blades, the pitch of the blades will be decreased when the drive shaft decelerates and increase when the drive shaft accelerates,

thereby tending to effect constant speed control.

Attention is directed to the fact that when the drive shaft and the inertia member rotate at the same speed they are relatively stationary and therefore a small torque acting to turn the inertia member relative to the drive shaft will effect relative rotation as such torque is resisted merely by the friction between the parts. It is well known that propeller blades are subject to torque reactions tending to turn them about their axes, and therefore it is necessary to employ 'a nonreversible power transmission mechanism between the inertia member and the blades in a constant speed control device and also in the variable pitch device described. i

What I claim and desire to secure by Letters Patent is:

1; In an automatic pitch varying mechanism for propellers, comprising in combination, a drive shaft, a hub non-rotatably carriedthereby, a propeller blade carried by the hub and mounted'for limited rotation about its axis, an auxiliary shaft in axial alinement with the drive shaft,

means comprising an inertia inember carried by the auxiliary shaft and mounted for concentric rotation therewith, for producing relative rotation between the two shafts when the drive shaft is accelerated above a predetermined rate, means operated by the relative rotation of the two shafts I I for propellers, comprising in combination, a drive shaft, a hub non-rotatably carried thereby, a propeller blade carried by the hub and mounted for limited rotation about its axis, an auxiliary shaft in axial 'alinement with the drive shaft,

means comprising aninertia member carried by the auxiliary shaft and symmetrically arranged A with respect to the axis thereof for producing relative rotation between the two shafts when the .drive shaft is accelerated above a predetermined rate, means operated by the relative rotation of the two shafts for decreasing the pitch of the propeller blade when the drive shaft accelerates, and for increasing the pitch when it decelerates, and a friction clutch interposed between the auxiliary shaft and the inertia member,

3. In an automatic pitch varying mechanism for propellers, comprising in combination, a drive shaft, a hub non-rotatably carried thereby; a propeller bladecarried by the hub and mounted for limited rotation about its axis, an auxiliary shaft in axial alinement with the drive shaft, means comprising an inertia member carried by the auxiliary shaft and symmetrically arranged with respect to the axis thereof, for producing relative rotation between the two shafts when the drive shaft is accelerated above a predetermined rate, means operated. by the relative rotation on the two shafts for reducing the pitch of the propeller blade when the drive shaft accelerates, and increasing the pitch when it decelerates, stops for limiting the extent of relative rotation of the auxiliary and drive shaft in either direction, and a friction, clutch interposed between the auxiliary shaft and the inertia member.

4. In a variable pitch propeller, in combination, a drive shaft, having an axial opening,

an auxiliary shaft mounted for rotation in the opening, the auxiliary shaft having its outer surface provided with threads, a nut threaded thereon, means for holding the nut fro'm rotating relative to -'the drive shaft, means for holding the auxiliary sha'ft from axial movement,'an abutment, a spring encircling the auxiliary shaft and positioned between the nut and the abutment,

means comprising an inertia member connected with the auxiliary shaft, and symmetrically arranged with respect to the axis thereof, for rotating the auxiliary shaft relative to the drive shaft when the drive shaft is accelerated above a certain rate, a propeller hub non-rotatably carried by the drive shaft, a propeller blade carried by the hub and mounted for axial adjustment, and means for turning the propeller blade about its axis whenever the auxiliary shaft turns relative to the drive shaft.

5. In a. variable pitch propeller, in combination, a drive shaft having an axial opening, an auxiliary shaft mounted for rotation in the opening, the auxiliary shaft having its outer sur-' face provided with threads, a. nut threaded thereon, means for holding the nut from rotating relative to the drive shaft, means'for holding the auxiliary shaft from axial movement, an abutment, 2. spring encircling the auxiliaryshaft and positioned between the nut and the abutment, an inertia member connected with the auxiliary shaft, and symmetrically arranged with respect to the axis of the drive shaft, forrotating the auxiliary shaft relative to the drive'shaft whenthe drive shaft. is accelerated above a certain rate, a friction clutch interposed between the inertia member and the auxiliary shaft, a propeller blade carried by the drive shaft and mounted for axial adjustment, and means for turning the propeller blade about its axis whenever the auxiliary shaft turns relative to the drive shaft.

6. In a variable pitch propeller, in combination, a drive shaft having an axial opening, an auxiliary shaft mounted for rotation in the opening, the auxiliary shaft having a portion of its surface provided with threads, a nut threaded on the auxiliary shaft, means for holding the nut frornrotating relative to the drive shaft, means for holding the auxiliary shaft from axial movement, an abutment, a spring encircling the auxiliary shaft and positioned between the nut and the abutment, an inertia member connected with the auxiliary shaft, and symmetrically arranged with respect to the axis of the drive shaft, for rotating the auxiliary shaft relative to the drive shaft when the drive shaft is' accelerated above a certain rate, a propeller blade carried by the drive shaft and mounted for axial adjustment, means for turning the propeller blade about its axis whenever the auxiliary shaft turns relative to the drive shaft, and means comprising stops rotarily stationary with respect to the drive shaft, and cooperating stops movable with the auxiliary shaft for limiting the rotation of the latter.

'7. In a variable pitch propeller, in combination, a drive shaft having an axial opening, an auxiliary shaft mounted for rotation in the opening, the auxiliary shaft having its outer surface provided with threads, a nut threaded on the auxiliary shaft, means for holding the nut from rotating relative to the drive shaft, means for holding the auxiliary shaft from axial movement, an abutment, a spring encircling the auxiliary shaft and positioned between the nut and the abutment, an inertia member connected with the auxiliary shaft, and symmetrically arranged with respect to the axis of the drive shaft, for rotating the auxiliary shaft relative to the drive shaft when the drive shaft is accelerated above a certain rate, a friction clutch interposed between the inertia member and the auxiliary shaft, a propeller blade carried by the drive shaft and mounted for axial adjustment, means for turning the propeller blade about its 'axis whenever the auxiliary shaft turns relative to the drive shaft, and means for limiting the rotation of the auxiliary shaft relative to the drive shaft.

8. In a machine having a propeller shaft, means for rotating the shaft, and means for increasing and decreasing the speed of rotation thereof, a hub carried by the shaft and held from rotation relative thereto, a propeller blade carried by the hub and mounted for limited axial rotation, a member having a threaded surface, carried by the propeller shaft, in axial alinement therewith, a weight supported bythe propeller shaft for coaxial relative rotation, means coop vment for effecting a decrease in pitch of the propeller blade when the weight rotates relative to the propeller shaft when the latter accelerates and an increase in pitch when the shaft decelerates.

gagement with the threaded surface, an acceleration responsive device supported for concentric rotation relative to the drive shaft, means responsive to the relative rotation of the acceleration responsive device and the drive shaft, for

producing a relative rotation between the nut and the auxiliary shaft, means responsive to the movement of the nut'relative to the auxiliary shaft for varying the pitch of the propeller blade and, means providing an opposing yielding resistance to the rotation of the acceleration responsive device, relative to the drive shaft, in a direction opposite to that in which the latter rotates.

10. The combination with a variable pitch propeller having adjustable blades, of means for changing the pitch of the blades thereof, comprising an inertia member journalled about an axis concentric with the axis about which the propeller turns, and a non-reversible motion transmitting device for transmitting motion from the inertia member to the blades.

11. The combination with a variable pitch propeller having adjustable blades, of means for changing the pitch of theblades' thereof, comprising an inertia member journalled about an axis concentric with the axis about which the propeller turns, means, comprising a threaded member, for transmitting motion from the inertia member to the blades, 3. spring,- and means comprising a threaded member and a cooperating threaded element for increasing the tension of the spring when the inertia member lags relative to the propeller to resist the lagging action.

13. The combination with a variable pitch propeller having adjustable blades, of means for changing the pitch of the blades thereof, comprising an inertia member mounted for rotation about an axis concentric with the axis about which the propeller turns, a resilient yielding means for opposing the tendency of the inertia member to rotate relative to the propeller in a direction opposite to that in which the propeller rotates and, a non-reversible motion transmitting mechanism for transmitting motion from the inertia member to the blades.

14. The combination with a variable pitch propeller having adjustable blades, of means for changing the pitch of the blades thereof, comprising an inertia member journalled about an axis concentric with the axis about which the propeller turns, mechanism for transmitting motion from the inertia member to the blades to adjust their pitch, stops for limiting the rotation of the propeller blades and, a friction clutch interposed between the inertia member and the mechanism for adjusting the blades for preventing the formation of excessive strains when the blades reach the limits of pitchchange.

15. In a variable pitch propeller, in combination, a drive shaft, a propeller hub non-rotatably carried thereby, propeller blades carried by the 'hub and mounted for limited rotation about their axes, an auxiliary shaft carried by the drive shaft for relative coaxial rotation therewith, an inertia member operatlvely associated with the auxiliary shaft, a threaded member operatively connected to the auxiliary shaft for rotation relative to the drive shaft when the inertia member rotates rel- ,drive shaft, for increasing the tension of 'the spring when theinertia member rotates relative to the drive shaft in a direction opposite to that in which the drive shaft turns and, means comprising a threaded member for changing the pitch of the propeller blades when the inertia member rotates relative to the drive shaft.

16. -In an automatic pitch varying mechanism for propellers, in combination, a drive shaft, a hub non-r0tatably carried thereby, propeller blades carried by'the hub for limited rotation about their axes, an auxiliary shaft in axial alignment with'the drive shaft, an inertia member carried by the'auxiliary shaft for rotation relative to the hub, motion transmittingmeans between the inertia member and the blades for changing the pitch of the latterlwhen the inertia member turns relative to the hub, yielding means for controlling the lagging of the inertia mem-'- ber, relative to the drive shaft, in a direction opposite to that in which the drive shaft rotates,

stop means for limiting the rotation of the blades and, means comprising a friction clutch interposed between the inertia member and the blades for preventing the formation of excessive strains.

17. In a variable pitch propeller having adjustable blades, in combination, a drive shaft, a bearing for said shaft, a propeller hub carried by the shaft, adjacent one side of the bearing an inertia member carried by the shaft on the opposite side of the bearing, the inertia member being mounted for rotation relative to the shaft and concentrically therewith, and means interposed between the inertia member-and the blades for varying the pitch angle of the latter when the inertia-member rotates relative to the drive shaft.

' 18. In a variable pitchpropeller having adjustable blades, in combination, a drive shaft, -a

' bearing for said shaft, a propeller hub carried by the shaft, adjacent one side of the bearing, an inertia member carried by the shaft on the opposite side of the bearing, the inertia member being mounted for rotation relative to the shaft and concentrically therewith, and means comprising a threaded member for transmitting motion from the inertia member to. the propeller blades to effect a pitch adjustment thereof when the inertia member rotates relative to the shaft.

19. In a variable pitch propeller having adjustable blades, in combination, a drive shaft,

a bearing for said shaft, a propeller hub carried by the shaft, adjacent one side of the bearing, an inertia member carried by the shaft on the opposite side of the-bearing, the inertia member being mounted for rotation relative to the shaft and concentrically therewith, means for' transmitting motion from the inertia member to the propeller blades toelfect a pitch adjustment of the latter when the inertia member rotates relative to the shaft, stop means for limiting the rotation of the blades, anda friction clutch inter,-

-posed between the inertia member and the motion transmitting means for preventing the-formation of excessive strains.

20. In ,a variable pitchpropeller having adjustable blades, in combination, a drive shaft, a bearing for said shaft, a propeller hub carried by the shaft, adjacent one side of the bearing, an inertia member carried by the shaft on the opposite side of the bearing, the inertia member being mounted for rotation relative to the shaft and concentrically therewith, means for transposed between the inertiamember and the mo,- tion transmitting means for preventing the formation of excessive strains, and resilient yielding means providing a force opposing the relative rotation of the inertiamember and the drive shaft in a direction opposite to that in which the drive shaft rotates.

21. The combination-with a variable pitch propeller having adjustable blades, of means for changing the pitch of the blades thereof, comprising an inertia member journalled about an axis concentric with the axis about which the propeller turns, means for modifying the action of the inertia member comprising complemental threaded members mounted for relative rotation, resilient yielding means for opposing relative rotation between the threaded members when the inertia member rotates relative'to the propeller in a direction opposite to the direction in which the propeller is turning, and stop means for limiting the relative rotation of' the complemental threaded members.

'22. The combination with a variable pitch propeller having adjustable blades, of means for 'of the inertia member comprising complemental threaded members mounted for relative rotation, yielding means, for opposing relative rotation between the threaded members when the inertia member rotates relative to the propeller in a direction opposite to the direction in which the propeller is turning, and a non-reversible motion transmitting mechanism, for transmitting motion from the inertia member to the blades.

23. The combination with a variable pitch propeller having adjustable blades, of means for changing the pitch ,of the blades thereof, comprising an inertia member mounted for rotation about an axis concentric with the axis about which the propeller turns, and means responsive to the rotation of the inertia member relative to the propeller for changing the pitch of the blades direction opposite .to that, in which the latter. is

turning. I

24. A variable pitch propeller comprising'in combination, 'a. drive shaft, a hub non-rotatably carried thereby, a propeller blade carried bythe hub and mounted for limitedrotation about its axis, an auxiliary shaft coaxial with the drive .shaft, and mounted for rotation relative thereto,

means responsive to variations in accelerations' of the drive shaft, comprising an inertia member carried by the auxiliary shaft, and mounted 'for rotation about the axis thereof, for produc-- ing relative rotation between the auxiliary shaft and the drive shaft and, means operated by the relative rotation of the auxiliary shaft and the drive shaft, comprising a member movable in the direction of the axis of the drive shaft for turning the propeller blade about its axis when rotation of the,blades, a friction clutch interthe auxiliary shaft and the drive shaft rotate relative to each other.

25. The combination with a variable pitch propeller having adjustable blades, of means for changing the pitch of the blades, comprising an.

inertia member mounted for rotation about an axis concentric with the axis about which the propeller turns, and resilient yielding means operatively associated with the inertia member for resisting its rotation relative to the propeller in the direction opposite to that in which the propeller rotates, the last mentioned means comprising a non-reversible mechanism for compressing the yielding means when the inertia member lags relative to the propeller.

26. The combination with a variable pitch propeller having adjustable blades of means for changing the pitch of the blades between predetermined limits, said means comprising an inertia member 'journaled about an axis concentric with the axis about which the propeller turns,

mechanism for transmitting movement from the inertia member to the blades when the inertia member rotates relative to the propeller shaft and a friction clutch interposed in the motion transmitting mechanism for the prevention of undue strains when the limits of pitch adjustment have been reached.

2'7. In a variable pitch propeller, in combination, a drive shaft, a propeller carried thereby, the propeller having blades mounted for pitch adjustment, an inertia member supported by the drive shaft for relative coaxial rotation, and mechanism comprising a friction clutch for effecting apitch adjustment of the blades commensurate with the extent of the relative rotation of the inertia member and the drive shaft, stops for limiting the pitch adjustment, the friction clutch being positioned between the inertia member and the stops.

DANIEL G. LILLEY. 

